Annual report pursuant to Section 13 and 15(d)

Stockholders' equity - Stock Option Activity (Details)

v2.4.0.8
Stockholders' equity - Stock Option Activity (Details) (USD $)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Exercise Price Per Share [Abstract]      
Granted, Exercise Price Lower Range Limit (usd per share) $ 3.2    
Granted, Exercise Price Upper Range Limit (usd per share) $ 4.5    
Canceled and Forfeited, Exercise Price Lower Range Limit (usd per share)   $ 1.20  
Canceled and Forfeited, Exercise Price Upper Range Limit (usd per share)   $ 2.60  
Tecogen
      
Stock Options Outstanding [Roll Forward]      
Beginning (shares) 1,096,500 1,095,250  
Granted (shares) 76,500 17,500  
Exercised (shares) (25,000) 0  
Canceled and forfeited (shares) 0 (15,938)  
Expired (shares) 0 (313)  
Ending (shares) 1,148,000 1,096,500 1,095,250
Exercisable (shares) 799,500 662,563  
Vested and expected to vest (shares) 1,148,000 1,096,500  
Weighted Average Exercise Price [Roll Forward]      
Beginning (usd per share) $ 1.96 $ 1.92  
Granted (usd per share) $ 3.86 $ 3.20  
Exercised (usd per share) $ 0.12 $ 0.00  
Canceled and forfeited (usd per share) $ 0.00 $ 1.28  
Expired (usd per share) $ 0.00 $ 2.60  
Ending (usd per share) $ 2.13 $ 1.96 $ 1.92
Exercisable (usd per share) $ 1.79 $ 1.56  
Vested and expected to vest (usd per share) $ 2.13 $ 1.96  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]      
Outstanding, Weighted Average Remaining Life 5 years 9 months 20 days 4 years 7 months 28 days 5 years 6 months 11 days
Outstanding, Aggregate Intrinsic Value $ 2,721,100 $ 1,356,400 $ 1,387,150
Exercisable, Aggregate Intrinsic Value 2,166,550 1,096,225  
Vested and expected to vest, Aggregate Intrinsic Value 2,721,100 1,356,400  
Exercise Price Per Share [Abstract]      
Outstanding, Exercise Price Lower Range Limit (usd per share) $ 1.20 $ 0.12 $ 0.12
Outstanding, Exercise Price Upper Range Limit (usd per share) $ 4.50 $ 3.20 $ 2.80
Granted, Exercise Price (usd per share)   $ 3.20  
Exercised, Exercise Price (usd per share) $ 0.12 $ 0  
Canceled and Forfeited, Exercise Price (usd per share) $ 0    
Expired, Exercise Price (usd per share) $ 0.00 $ 2.60  
Ilois
      
Stock Options Outstanding [Roll Forward]      
Beginning (shares) 575,000 525,000  
Granted (shares) 0 50,000  
Exercised (shares) 0 0  
Canceled and forfeited (shares) 0 0  
Expired (shares) 0 0  
Ending (shares) 575,000 575,000 525,000
Exercisable (shares) 0 0  
Vested and expected to vest (shares) 575,000 575,000  
Weighted Average Exercise Price [Roll Forward]      
Beginning (usd per share) $ 0.29 $ 0.27  
Granted (usd per share) $ 0.00 $ 0.50  
Exercised (usd per share) $ 0.00 $ 0.00  
Canceled and forfeited (usd per share) $ 0.00 $ 0.00  
Expired (usd per share) $ 0.00 $ 0.00  
Ending (usd per share) $ 0.29 $ 0.29 $ 0.27
Exercisable (usd per share) $ 0.50 $ 0.00  
Vested and expected to vest (usd per share) $ 0.29 $ 0.29  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]      
Outstanding, Weighted Average Remaining Life 6 years 5 months 9 days 7 years 5 months 7 days 8 years 2 months 22 days
Outstanding, Aggregate Intrinsic Value 120,000 120,000 120,000
Exercisable, Aggregate Intrinsic Value 0 0  
Vested and expected to vest, Aggregate Intrinsic Value $ 120,000 $ 120,000  
Exercise Price Per Share [Abstract]      
Outstanding, Exercise Price Lower Range Limit (usd per share) $ 0.10 $ 0.10 $ 0.10
Outstanding, Exercise Price Upper Range Limit (usd per share) $ 0.50 $ 0.50 $ 0.5
Granted, Exercise Price (usd per share) $ 0 $ 0.50  
Exercised, Exercise Price (usd per share) $ 0 $ 0  
Canceled and Forfeited, Exercise Price (usd per share) $ 0 $ 0  
Expired, Exercise Price (usd per share) $ 0 $ 0